Information
-
Patent Grant
-
6796244
-
Patent Number
6,796,244
-
Date Filed
Thursday, April 3, 200321 years ago
-
Date Issued
Tuesday, September 28, 200419 years ago
-
Inventors
-
Original Assignees
-
Examiners
- Keith; Jack W.
- Bergin; James S.
Agents
-
CPC
-
US Classifications
Field of Search
US
- 102 340
- 102 342
- 102 351
- 102 357
- 102 377
- 102 378
- 102 393
- 102 481
- 102 489
- 102 517
- 102 524
- 102 473
- 102 501
- 102 503
- 102 504
- 102 505
- 102 477
-
International Classifications
-
Abstract
A ballistic projectile (10) includes a body (12) defining a hollow, open-ended payload cavity (22) covered by means of a cover portion (26) fitting as a spigot into a socket (12.1) defined by the body (12). Peripheral seats in the form of grooves (32), (34) are provided in register in peripheral slide surfaces of respectively the cover portion (26) and the body (12) forming the spigot-socket combination. A peripheral, discontinuous shear ring (36) is received within the respective grooves (32), (34) to bridge the interface and thus to lock the cover portion to the body. Pressure selectively generated in the payload cavity shears the ring (36) to allow parting of the cover portion to expose the payload cavity.
Description
In accordance with a first aspect of this invention, there is provided a ballistic projectile including
a body portion defining an internal cavity and having a surround around the cavity, the surround having a peripheral slide surface;
a cover portion having a peripheral slide surface complemental to said slide surface of the surround to render the body portion and the cover portion slidably closable onto each other to close the cavity;
complementally arranged peripheral seats in the respective slide surfaces, and a generally peripheral band seated in said seats such that the band bridges an interface between, and inter-secures, the body portion and cover portion.
The projectile may be round.
At least one of the surround, the cover portion and the peripheral band may be resilient to allow assembly. In practice, the peripheral band may be resilient. Thus, in a preferred embodiment, the slide surfaces may be round, and the band may be in the form of a resilient ring.
The resilient ring may be a split ring to allow a cross dimension thereof to be reduced/increased by compression/expansion, one of the seats being of sufficient capacity to accommodate the ring fully to allow the ring to be strained fully into said one seat to cause the ring to be flush with or shy of the corresponding slide surface.
Advantageously the seats and the band may be arranged to be concealed when assembled to render the projectile unopenable from externally and thus tamper proof.
Preferably, the band or the resilient ring may be a shear ring designed to fail at a predetermined shear force. Then, the ballistic projectile may include a pressure generator for generating internal pressure to a corresponding, predetermined pressure to shear the ring and to cause the cover portion to part from the body portion to expose the cavity. The ballistic projectile may be a base ejection projectile, the projectile including a pressure generator in the form of a propellant charge for generating internal pressure to a predetermined value to shear the ring and to cause the cover portion to part from the body portion to expose the cavity.
In accordance with a second aspect of the invention, there is provided a method of closing a ballistic projectile in accordance with the first aspect, the method including
seating the band in one of the seats;
straining the band to be fully received within said one seat;
retaining the band fully in said one seat and closing the cover portion onto the body portion to register the seats;
causing the band to relax to move only partially out of said one of the seats and to move partially into the opposing other of the seats interlockingly to inter-secure the body portion and the cover portion.
The peripheral slide surface of the cover portion may fit inside the peripheral slide surface of the surround, the method including compressing the ring into the seat by means of a compression sleeve covering only a portion of the ring to allow the uncovered portion to be slid within the surround to hold the ring to allow the compression sleeve to be removed to allow the ring to be slid into register with the opposing seat. Once registered, the ring expands under its resilience to enter the opposing seat to bridge the interface.
In accordance with a third aspect of the invention, there is provided a method of opening a ballistic projectile in accordance with the first aspect, the method including generating pressure within the enclosed cavity to a sufficient degree to shear the band to cause the cover portion to part from the body portion under the internal pressure. Thus, generating internal pressure may be by initiating a propellant charge exposed to the cavity.
The method of opening the ballistic projectile may include the prior step of providing sealing between the respective slide surfaces to facilitate internal pressure generation.
The invention is now described by way of example with reference to the accompanying diagrammatic drawings. In the drawings
FIG. 1
shows, in axial section, a base ejection, ordnance gun projectile in accordance with the invention; and
FIG. 2
shows, in three-dimensional, cut-away, fragmentary view to a larger scale, a base portion of the projectile of FIG.
1
.
With reference to the drawings, a projectile of the kind used with ordnance guns is generally indicated by reference numeral
10
. The projectile has a body
12
tapering toward a leading end
14
housing a fuse
16
immediately ahead of an ejection charge
18
.
The body
12
extends in generally parallel fashion rearwardly toward a trailing end
20
where it terminates, boat tail-fashion, at a rear end
24
. A cavity
22
for a payload is formed within the body
12
.
The trailing end
20
is formed by a base
26
in the form of a disc having a peripheral rim
28
and a recess
30
along an axially inner, radially outer extremity of the rim. As can be seen in
FIG. 2
, the recess
30
forms a short cylindrical slide surface
30
.
1
and an annular abutting surface
30
.
2
, generally at right angles to each other. The slide surface
30
.
1
forms an outer surface in accordance with this invention. The inner periphery of an end portion of the body
12
is in the form of a slide surface
12
.
1
which slides along and over the slide surface
30
.
1
with little clearance. In some embodiments, slight interference to ensure a slight frictional fit with the attended sealing may be preferred. The end wall
24
abuts the abutting surface
30
.
2
.
In accordance with the invention, in the base
26
, and more specifically in the slide surface
30
.
1
, there is provided a peripheral seat in the form of a groove indicated by reference numeral
32
. A corresponding seat in the form of a groove
34
is provided in the inner periphery of the body
12
, more specifically the slide surface
12
.
1
, such that the grooves
32
,
34
will be mutually opposing and indexed when the end wall
24
abuts the abutting surface
30
.
2
.
A resilient shear ring
36
which is in the form of a split ring as indicated by reference numeral
38
, fits with little axial clearance within the groove
32
. The ring
36
is resilient and the split
38
is sufficiently large to allow the ring
36
to be compressed such that it fits completely within the groove
32
, i.e. such that an outer periphery of the ring
36
will be flush with or shy of the slide surface
30
.
1
. When held in that configuration, the body
12
and more specifically the slide surface-
12
.
1
formed by the end portion can be slid over the slide surface
30
.
1
and over the groove
32
with the ring
36
retained therein. When the end wall
24
abuts the abutting surface
30
.
2
and the grooves
32
,
34
are indexed, the ring
36
, under its resilience, expands to enter also the groove
34
and thus to bridge the interface between the slide surface
30
.
1
and the slide surface
12
.
1
. Thus, the ring
36
interlocks the base
26
and the body
12
against relative axial sliding and thus causes locking of the base
26
onto the body
12
.
It is important to appreciate that the ring
36
may, instead, be strained by expansion to be accommodated fully within the outer groove
34
to allow assembly and, when the grooves are indexed, it will retract under its resilience to move also into the inner grove
32
.
The shearing function of the ring, which is most important in the context of this specification, is explained below.
In respect of sealing, it is important to appreciate that the degree of sealing required can generally be effected by means of a close or a very light interference fit which would add to the parting or separating force required to overcome friction, but which would be very much less than the force required if no shear ring is used and total reliance is placed on friction to effect securement of the components. Thus, the separation force required to overcome the interference fit, which is difficult to control and which varies widely, is a low percentage of the total separation force and thus adds correspondingly little to the overall uncertainty or variation in separation force.
Instead of a close or a light interference fit, sealing may be effected by means of a sealing substance, such as a lubricant or sealant, applied between the slide surfaces.
As a further option, the slide surfaces
30
.
1
and
12
.
1
may be complementally frusto-conical at a shallow angle to improve fit and sealing.
It is of significance that the end wall
24
abuts fully against the abutting surface
30
.
2
when the grooves are indexed. Thus, there is no or virtually no lost motion between the abutting surface
30
.
2
and the end wall
24
, where there would be some lost motion between the ring
36
and sides of the grooves
32
,
34
. Thus, launching the projectile
10
from an ordnance gun which entails very high pressure at the trailing end
20
, causes acceleration force to be transferred from the base
26
via the abutting surface
30
.
2
and the end wall
24
to the projectile body, and no force to be transmitted via the shear ring
36
. Furthermore, because of the very high surface force transmitted from the abutting surface
30
.
2
to the end wall
24
, spinning of the projectile through the barrel of the ordnance gun and the associated torque is also transmitted frictionally via those abutting surfaces. It is to be understood that, because of the very high pressure between those surfaces, friction forces are high i.e. substantially higher than what is required to transmit torque associated with spin. In the illustrated embodiment, spin is imparted to the body
12
via a propelling band proximate the end wall
24
and torque to spin only the base
26
, which has relatively low inertia, is transmitted frictionally.
It is of great importance that the shear ring
36
is dormant during launching and normal flight of the projectile and that it is not stressed at all. Thus, the shear ring
36
and the characteristics thereof can be selected totally independently of requirements relating to launching and the flight of the projectile.
When the payload cavity
22
is to be exposed, the ejection charge
18
is initiated causing pressure to be generated within the payload cavity
22
.
When the pressure within the cavity
22
corresponds to the failing shear force of the ring
36
, the ring
36
shears and allows the pressure to separate the base
26
from the body
12
thus exposing the payload cavity
22
.
It is important to appreciate that the shear force required to shear the ring
36
can be pre-selected over a wide range bearing in mind a number of design variables available, namely the material of the ring
36
, the profile of the ring
36
and the thickness of the ring
36
along a shear line. The ring
36
may, for example be of metal, but it is expected to be mostly, advantageously, of a synthetic polymeric material selected to have appropriate shear characteristics.
It is of importance that the projectile, when closed in accordance with the invention, is tamper proof. It is to be appreciated that special tooling and some expertise are required easily to assemble a projectile, however, when such special tooling and expertise are available, assembling of the projectile is very cost efficient both in respect of time and the consumable namely the ring. This leads to another advantage in that, should the projectile be required to be opened prior to actual use, it can easily be done by shearing the shear ring
36
which is thus sacrificed. As mentioned above, such shear ring is inexpensive and the projectile can easily be reassembled by merely using a fresh shear ring. It is important that the projectile itself, including the grooves, is not damaged at all but that merely the shear ring is sacrificed.
Although the invention has been described with reference to a base ejection projectile for an ordnance gun, it will readily be appreciated that the invention is easily applicable to closing of any hollow body of a ballistic missile in tamper proof fashion and such that the body can easily be opened by means of a controlled internal pressure.
Claims
- 1. A ballistic projectile includinga body portion defining an internal cavity and having a surround around the cavity, the surround having a longitudinal, round peripheral, slide surface; a cover portion having a longitudinal, round peripheral, slide surface complemental to said slide surface of the surround to render the body portion and the cover portion longitudinally slidably closable onto each other to close the cavity and an annular abutting surface which is inseparably fixed to, is generally at right angles to, and stands proud of the slide surface of the cover portion; complementally arranged peripheral seats in the respective slide surfaces, and a resilient generally peripheral ring which is a split ring to allow a cross dimension thereof to be reduced/increased by compression/expansion, one of the seats being of sufficient capacity to accommodate the ring fully to allow the ring to be strained fully into said one seat to cause the ring to be flush with or shy of the corresponding slide surface to allow the other of the slide surfaces to be slid past said one seat accommodating the ring fully, to index the seat to allow the ring to relax to enter said other seat such that the ring bridges an interface between, and intersecures, the body portion and the cover portion, the annular abutting surface covering said interface and rendering said peripheral ring concealed and rendering the projectile unopenable from externally and thus tamperproof.
- 2. A ballistic projectile as claimed in claim 1 in which the ring is a shear ring designed to fail at a predetermined shear force.
- 3. A ballistic projectile as claimed in claim 2 which includes a pressure generator for generating internal pressure to a corresponding, predetermined pressure to shear the ring and to cause the cover portion to part from the body portion to expose the cavity.
- 4. A ballistic projectile as claimed in claim 3 which is a base ejection, projectile, the projectile including a pressure generator in the form of a propellant charge for generating internal pressure to a predetermined value to shear the ring and to cause the cover portion to part from the body portion to expose the cavity.
- 5. A method of closing a ballistic projectile as claimed in claim 1, the method includingseating the ring in one of the seats; straining the ring to be fully received within one said seat; retaining the ring fully in said one seat and closing the cover portion onto the body portion to register the seats; causing the ring to relax to move only partially out of said one of the seats and to move partially into the opposing other of the seats interlockingly to inter-secure the body portion and the cover portion.
- 6. A method as claimed in claim 5, in which the ring is seated and strained to be fully received and retained in the seat which is in a radially inner of the slide surfaces.
- 7. A method as claimed in claim 6, in which said radially inner of the slide surfaces, is in the cover portion.
Priority Claims (1)
Number |
Date |
Country |
Kind |
2002-9842 |
Dec 2002 |
ZA |
|
US Referenced Citations (5)
Foreign Referenced Citations (2)
Number |
Date |
Country |
395456 |
Oct 1990 |
EP |
2705144 |
May 1993 |
FR |